1. Field of the Invention
The present invention relates to an indwelling needle assembly to be pricked into and indwelled in a blood vessel when carrying out fluid infusion or drawing of blood and to a needle protector for protecting a needle point of a needle of an indwelling needle assembly, an injection needle or the like.
2. Description of the Prior Art
When carrying out fluid infusion or drawing of blood for a patient, an indwelling needle including a metallic needle for pricking into the patient's skin (inner needle) and a resin needle (outer needle) for being indwelled in the patient's blood vessel arranged on the outer periphery of the inner needle is used. The inner needle of the indwelling needle has a sharp needle point, and may cause an accident such as erroneous puncture when withdrawing the inner needle from the outer needle to leave only the outer needle indwelled in the patient after use.
So far, when discarding an inner needle after use, procedures such as reinserting the inner needle into a package in which the needle had been stored before use or reinserting the needle point of the inner needle into a cap which had been covering the needle point before use have been taken. However, close attention must also be paid not to cause erroneous puncture with the needle point during such procedures, and hence, these measures cannot successfully reduce the risk of an erroneous puncture.
In order to reduce the probability of erroneous puncture as described above, indwelling needle assemblies provided with an erroneous puncture preventing mechanism, which protects the sharp needle point of the inner needle from being exposed when the inner needle is withdrawn from the outer needle, have started to be widely used in recent years.
As an example of such an erroneous puncture preventing mechanism, there is a protector which is arranged on the inner needle so as to be slidable axially on the needle, and is capable of storing the needle point in the interior thereof. Examples of the protector described above are an indwelling needle assembly provided with a cylindrical protector having a plurality of inwardly urged fingers at a distal end thereof (see Patent Document 1) or an indwelling needle assembly provided with a protector composed of an elastic spring clip having walls at the front and rear (see Patent Document 2, 3 or 4).
The protector in these indwelling needle assemblies has openings at two or more points, that is, on the side of a needle point (distal side) and on the side of a needle root (proximal side) for allowing insertion of the needle, and is fixedly engaged in the interior of an outer needle hub in a state before usage of the indwelling needle. When the inner needle is pulled out from the proximal side of the outer needle after having pricked the indwelling needle into the patient, the protector is maintained in a fixed state on the outer needle hub. Therefore, the needle point of the inner needle passes through the opening on the distal side of the protector, and is stored in the protector for protection. Then, the engagement between the protector and the outer needle hub is released, and the protector is completely pulled out from the outer needle together with the inner needle. The distal end portion of the protector has an inwardly urged portion, so that when pulling out the inner needle, the opening is closed immediately after the needle point has passed through the opening on the distal side and the needle point is prevented from being exposed again from the distal end portion of the protector. Therefore, the distal end portion of the protector is constantly in press-contact with the outer periphery surface of the inner needle in a state before the inner needle is pulled out, which increases a sliding resistance against the movement of the protector on the inner needle and increases a force required for protecting the needle point.
[Patent Document 1] JP-A-9-99073
[Patent Document 2] JP-T-2001-514943
[Patent Document 3] JP-A-2002-248168
[Patent Document 4] JP-A-2002-210005